Mobile phones come equipped with a vast array of actuation and sensing technologies, making them an ideal platform for point-of-care diagnostics and information gathering. Mobile phone microscopes take advantage of the small pixel size on mobile phone camera sensors for micron-scale resolution. Focusing can be achieved with built-in autofocus and image processing can be done on-board, however, the illumination is typically introduced via an external light emitting diode (LED). These external LEDs are typically externally powered, adding bulk and cost to a system that is meant to be as affordable as possible. In this work, we present a mobile phone microscope that uses the phone's integrated flash as an illumination source, eliminating the need to engineer an external illumination into the system. Our design consists of a 3D printed clip-on module containing a lens, which together with the mobile phone camera lens acts as an infinite-conjugate microscope. The clip-on module functions as a basic sample holder, and contains a series of light tunnels that redirect light from the flash through the sample for brightfield illumination. Instead of mirrors and a condenser lens, diffuse reflection from the internal light tunnel of the plastic clip-on module both reflects and scatters light into a range of illumination angles – ideal for brightfield microscopy. For low-contrast samples, darkfield imaging is achieved with ambient lighting via internal reflection within the sample microscope slide. We demonstrate imaging and video microscopy of a range of samples including plants, cell cultures and cattle semen.
The direct write of photonic elements onto substrates presents opportunities for rapid prototyping and novel sensing architectures in domains inaccessible to traditional lithography. In particular, focussed electron beam induced deposition (FEBID) of platinum is a convenient technology for such direct-write applications with the advantage of relatively controlled deposition parameters and sub-10 nm resolution. One issue for FEBID of platinum is that the precursor gas contains a relatively high carbon content, which in turn leads to carbonaceous deposits in the final structure. Here we explore the creation of plasmonic nanoantennae using FEBID platinum. We compare as-deposited and annealed antenna with heights of 40 nm and 56 nm, showing the effect of annealing on the carbon concentration and hence the optical properties. These results are compared with modelling using Mie scattering theory. Our results show that FEBID platinum is a useful material for the direct-write of plasmonic nanoantenna.
We report the generation of sub-surface nanouidic channels from single crystal diamond. To make the channels, we used a combination of ion-beam induced damage and annealing to create a buried, etchable graphitic layer in the diamond. Either laser or focussed ion-beam milling was then used to connect to that layer, and subsequent electro-chemical etching used to remove the graphitic material. The channels had dimensions 100-200 nm thick, 100 μm wide and 300 μm long, which have a total volume around 3 pL; and were around 3 μm below the diamond surface.
The porous properties of self-assembled waveguides made up of nanoparticles are characterised. Atomic force microscopy (AFM) reveals predominantly hcp or fcc packing suggesting a remarkably well ordered and distributed porous structure. N2 adsorption studies estimate a surface area SA ~ 101 m2/g, a total interstitial volume Vi ~ 1.7 mL/g and a pore size distribution of r ~ (2 - 6) nm. This distribution is in excellent agreement with the idealised values for identically sized particles obtained for the octahedral and tetrahedral pores of the hcp and fcc lattices, estimated to lie within and rtet ~ (2.2 – 3.3) nm and roct ~ (4.2 – 6.2) nm for particles varying in size over 20 to 30 nm. Optical transmission based percolation studies reveal rapid penetration of Rhodamine dye (< 5 s) with very little percolation of larger molecules such as ZnTPP observed under similar loading conditions. In the latter case, laser ablation was used to determine the transport of hydrated Zn2+ to be D ~ 3 x 10-4 nm2s-1. By comparison, ZnTPP was not able to percolate into the wire over the time of exposure, t = 10 mins, effectively demonstrating the self-assembled structure acting as a molecular sieve. We discuss the potential of such structures more broadly and conclude that the controllable distribution of such nano-chambers offers the possibility of amplifying, or up-scaling, an otherwise local interaction or nanoreactions to make detection and diagnostics much simpler; it also opens up a new approach to material engineering making new composites with periodic nanoscale variability. These and other unique aspects of these structures are embodied in an overall concept of lab-in-wire, or similar self-assembled structures, extending our previous concept of lab-in-fibre from the micro domain into the nano domain.
Recent advances in the production of high-purity synthetic diamonds have made diamond an accessible host material for
applications in present and future optoelectronic and photonic devices. We have developed a scalable process for
fabricating photonic devices in diamond using reactive ion etching (RIE) and photolithography as well as using ion
implantation to provide vertical confinement. Applying this we have demonstrated a few-moded waveguide with a large
cross section for easier coupling to optical fibre. We present our work towards in-plane coupling to diamond waveguides
and consequently characterisation of these waveguides. We also examine the application of diamond waveguides to other
photonic applications for achieving light confinement in a subwavelength cavity site using a slot-waveguide design. Such
cavities may be used to enhance photon-emission properties of a built-in diamond colour centre and to achieve strong
light-matter interactions on the single-quantum level necessary for quantum information technology. Using single
cavities as building block, we also show that these structures can be suitably coupled to form one-dimensional coupled-resonator
Diamond has a range of extraordinary properties and the recent ability to produce high quality synthetic diamond has
paved the way for the fabrication of practical diamond devices. This paper details the recent progress in the fabrication of
waveguide structures in diamond which are desirable as the basis for quantum key distribution (QKD), quantum computing and high-power, high speed microwave chips. The diamond ridge waveguide structures are produced by photolithography and reactive ion etching (RIE) with some additional processing with a focused ion beam (FIB). The processes currently used are discussed along with experimental results. Future fabrication goals and potential methods for achieving these goals are also presented.
Resonant nanostructured metallic devices have attracted considerable recent attention through phenomena such as
extraordinary transmission and their potential application as sensing elements, metamaterials and for enhancing
nonlinear optical effects. Here we report on the investigation of the geometry and material properties on the performance
of periodic and random arrays of coaxial apertures in thin metallic films. Such apertures in perfect conductors have been
shown to resonate at a wavelength governed by the geometry of the apertures leading to enhanced transmission. This
resonant wavelength is dictated by the cutoff wavelength of the fundamental mode propagating in the corresponding
coaxial waveguide and, as a consequence, is largely independent of whether the apertures are isolated or in random or
periodic arrangements. In the case of periodic samples, however, these resonances can coherently couple to surface
waves to produce an analogue of the enhanced optical transmission seen in arrays of circular and other apertures. We
have previously shown that as the width of the rings decreases, there are substantial red-shifts in the resonant wavelength
from that predicted for perfect conductivity when the optical properties of the metal are considered. Here we report on
recent developments in fabrication, design and modelling of metallic resonant structures and their near- and far-field
optical characterisation. In particular, we consider the relationship between random and regular arrangements of
The near and far-field transmission characteristics of nanoscale annular array metamaterials fabricated using ion beam
lithography are investigated both computationally and experimentally. Experimental results in the far-field regime
demonstrate high transmission efficiencies in the near infra-red region of the electromagnetic spectrum for these devices,
in excellent qualitative agreement with a previously developed numerical model. The diffractive near-field behavior of
such structures is discussed, with a particular emphasis on the implications associated with verifying such predictions
We describe how a quantum non-demolition device based on electromagnetically-induced transparency in solidstate atom-like systems could be realized. Such a resource, requiring only weak optical nonlinearities, could potentially enable photonic quantum information processing (QIP) that is much more efficient than QIP based on linear optics alone. As an example, we show how a parity gate could be constructed. A particularly interesting physical system for constructing devices is the nitrogen-vacancy defect in diamond, but the excited-state structure for this system is unclear in the existing literature. We include some of our latest spectroscopic results that indicate that the optical transitions are generally not spin-preserving, even at zero magnetic field, which allows the realization of a Λ-type system.